Now to the frightening scene in miami. New here this evening, the 911 calls after the deck at a popular sports place suddenly collapsed. Tonight the hidden signals our own deck could be next. ReporteHEERS MUTATING Into screams. Are you okay? Reporter: Heard tonight on these 911 calls. The dock fell in the water. The whole deck and the whole bar fell and everyone's in the water and I don't know if they're okay. Reporter: The deck crashing into the bay. Is everybody out? Reporter: Dumping 100 patrons packed in to watch the nba finals. We took a boat to survey the damage. You can see the force of the collapse folded the concrete pilings, smashing everybody inside. No fatalities, but 24 people rushed to the hospital. Investigators say this happens more than you think. Posing for the prom. Last month, this wedding party tumbling into a lake. How to spot the warning signs on your own deck. Look for cracked and rotted woods. Decked poorly bolted to the building. Corrosion, and listen for creeking. Something witnesses in miami told us they heard. IT STARTEDs CREEKING AND IT Collapsed.

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